This invention relates generally to fusing apparatus in electrostatographic copiers and printers for fusing toner images to suitable receivers or copy sheets of paper, and more particularly to such an apparatus that includes an axially unsupported fuser roller.
In electrostatographic copiers and printers, conventional heat and pressure fusing apparatus as disclosed, for example in U.S. Pat. No. 4,551,006, issued Nov. 5, 1985 in the name of Elvin, include a pair of rollers, each generally of a hollow metallic core that may be coated with a layer of compliant material such as an elastomer. Heat necessary for fusing is supplied to at least one of the rollers, usually the roller that directly contacts the toner images being fused. Such heat may be supplied by a heat source or lamp located within the hollow of the metallic core of such roller, or alternatively, by an external heat source that contacts and directly heats the surface of the one roller. Typically, the heated roller is the fused roller, while the other roller is the pressure roller. The pressure for fusing is supplied at the nip through cooperation between the fuser and pressure rollers. Whether heated internally or externally, such fuser and pressure rollers are conventionally axially supported to form a fusing nip through which the toner images are conveyed for fusing on a suitable receiver, or copy sheet of paper.
Axially supported rollers, however, may be expensive since they include axial mounting components such as gudgeons and bearings. In addition, axially supported rollers are not easy to service because the axial mounting components usually have to be disassembled during such service. Furthermore, axially supported rollers ordinarily rotate about a fixed axis, and hence are normally not capable of dissipating rotational strains and stresses that may cause fusing related defects such as copy sheet distortions, copy curls, wrinkles and image voids.